A combinatorial approach for the discovery of drug-like inhibitors of 15-lipoxygenase-1

Synthesis of new multitarget-directed ligands containing thienopyrimidine nucleus for inhibition of 15-lipoxygenase, cyclooxygenases, and pro-inflammatory cytokines

A new series of thieno[2,3-d]pyrimidine derivatives 4, 5, 6a-o, and 11 was designed and synthesized starting from cyclohexanone under Gewald condition with the aim to develop multitarget-directed ligands (MTDLs) having anti-inflammatory properties against both 15-LOX and COX-2 enzymes. Moreover, the potential of the compounds against the proinflammatory mediators NO, ROS, TNF-α, and IL-6 were tested in LPS-activated RAW 264.7 macrophages. Compound 6o showed the greatest 15-LOX inhibitory effect (IC₅₀ = 1.17 μM) which was superior to that of the reference nordihydroguaiaretic acid (NDGA, IC₅₀ = 1.28 μM); meanwhile, compounds 6h, 6g, 11, and 4 exhibited potent activities (IC₅₀ = 1.29-1.77 μM). The ester 4 (SI = 137.37) and the phenyl-substituted acetohydrazide 11 (SI = 132.26) showed the highest COX-2 selectivity, which was about 28 times more selective than the reference drug diclofenac (SI = 4.73), however, it was lower than that of celecoxib (SI = 219.25). Interestingly, compound 6o, which showed the highest 15-LOX inhibitory activity and 5 times higher COX-2 selectivity than diclofenac, showed a greater poteny in reducing NO (IC₅₀ = 7.77 μM) than both celecoxib (IC₅₀ = 22.89 μM) and diclofenac (IC₅₀ = 25.34), but comparable activity in inhibiting TNF-α (IC₅₀ = 11.27) to diclofenac (IC₅₀ = 10.45 μM). Similarly, compounds 11 and 6h were more potent in reducing TNF-α and IL6 levels than diclofenac, meanwhile, compound 4 reduced ROS, NO, IL6, and TNF-α levels with comparable potency to the reference drugs celecoxib and diclofenac. Furthermore, docking studies for our compounds within 15-LOX and COX-2 active sites revealed good agreement with the biological evaluations. The proposed compounds could be promising multi-targeted anti-inflammatory candidates to treat resistant inflammatory conditions.

Acylhydrazones and Their Biological Activity: A Review

Due to the structure of acylhydrazones both by the pharmacophore -CO-NH-N= group and by the different substituents present in the molecules of compounds of this class, various pharmacological activities were reported, including antitumor, antimicrobial, antiviral, antiparasitic, anti-inflammatory, immunomodulatory, antiedematous, antiglaucomatous, antidiabetic, antioxidant, and actions on the central nervous system and on the cardiovascular system. This fragment is found in the structure of several drugs used in the therapy of some diseases that are at the top of public health problems, like microbial infections and cardiovascular diseases. Moreover, the acylhydrazone moiety is present in the structure of some compounds with possible applications in the treatment of other different pathologies, such as schizophrenia, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Considering these aspects, we consider that a study of the literature data regarding the structural and biological properties of these compounds is useful.

Novel flavonoid hybrids as potent antiviral agents against hepatitis A: Design, synthesis and biological evaluation

Two series of flavonoid hybrids, totaling 42 compounds, were designed, synthesized and evaluated to develop antiviral compounds effective against hepatitis A virus (HAV). A recombinant viral screening system revealed that most of the synthesized derivatives exhibited significant anti-HAV activity, and compounds B2, B3, B5 and B27 were identified as potential inhibitors of HAV. Post-treatment of cells with B2, B3, B5 and B27 after HAV infection strongly suppressed HAV infection, whereas pretreatment or simultaneous treatment were ineffective. Furthermore, these four compounds significantly inhibited HAV (HM175/18f strain) production in a dose-dependent manner. Analyses using HAV subgenomic replicon systems indicated that these compounds specifically inhibit HAV RNA replication. More importantly, the most potent compounds B2 and B27 also showed clear inhibitory effects on two other HAV strains, KRM031 and TKM005, which also isolated from clinical patients. Our study is the first to report these newly designed flavonoid hybrids as lead compounds for the development of novel anti-HAV drugs.

Identification and synthesis of selective cholesterol esterase inhibitor using dynamic combinatorial chemistry

In this study, the concept of dynamic combinatorial chemistry (DCC) was applied to explore novel cholesterol esterase (CEase) inhibitors. In the presence of enzyme, two substrates (A1H3 and A2H3) were amplified from the dynamic combinatorial library (DCL), which was generated through reversible acylhydrazone formation reaction. In the in vitro biological evaluation, compound A1H3 exhibited not only potent (IC₅₀ in nanomolar range) but also selective inhibition (>120 folds of selectivity for CEase over AChE). Furthermore, the binding pattern and possible binding mechanism were investigated in the kinetic experiment and molecular docking study, respectively.

Functionalized Homologues and Positional Isomers of Rabbit 15-Lipoxygenase RS75091 Inhibitor

BACKGROUND

RS75091 is a cinnamic acid derivative that has been used for the crystallization of the rabbit ALOX15-inhibitor complex. The atomic coordinates of the resolved ALOX15-inhibitor complex were later used to define the binding sites of other mammalian lipoxygenase orthologs, for which no direct structural data with ligand has been reported so far.

INTRODUCTION

The putative binding pocket of the human ALOX5 was reconstructed on the basis of its structural alignment with rabbit ALOX15-RS75091 inhibitor. However, considering the possible conformational changes the enzyme may undergo in solution, it remains unclear whether the existing models adequately mirror the architecture of the ALOX5 active site.

METHODS

In this study, we prepared a series of RS75091 derivatives using a Sonogashira coupling reaction of regioisomeric bromocinnamates with protected acetylenic alcohols and tested their inhibitory properties on rabbit ALOX15.

RESULTS

A bulky pentafluorophenyl moiety linked to either ortho- or metha-ethynylcinnamates via aliphatic spacer does not significantly impair the inhibitory properties of RS75091.

CONCLUSION

Hydroxylated 2- and 3-alkynylcinnamates may be suitable candidates for incorporation of an aromatic linker group like tetrafluorophenylazides for photoaffinity labeling assays.

Novel 1,2,4-triazine-quinoline hybrids: The privileged scaffolds as potent multi-target inhibitors of LPS-induced inflammatory response via dual COX-2 and 15-LOX inhibition

Based on the observed pharmacophoric structural features for the reported dual COX/15-LOX inhibitors and inspired by the abundance of COX/LOX inhibitory activities reported for the 1,2,4-triazine and quinoline scaffolds, we designed and synthesized novel 1,2,4-triazine-quinoline hybrids (8a-n). The synthesized hybrids were evaluated in vitro as dual COXs/15-LOX inhibitors. The new triazine-quinoline hybrids (8a-n) exhibited potent COX-2 inhibitory profiles (IC₅₀ = 0.047-0.32 μM, SI ∼ 20.6-265.9) compared to celecoxib (IC₅₀ = 0.045 μM, SI ∼ 326). Moreover, they revealed potent inhibitory activities against 15-LOX enzyme compared to reference quercetin (IC₅₀ = 1.81-3.60 vs. 3.34 μM). Hybrid 8e was the most potent and selective dual COX-2/15-LOX inhibitor (COX-2 IC₅₀ = 0.047 μM, SI = 265.9, 15-LOX IC₅₀ = 1.81 μM). These hybrids were further challenged by their ability to inhibit NO, ROS, TNF-α, IL-6 inflammatory mediators, and 15-LOX product, 15-HETE, production in LPS-activated RAW 264.7 macrophages cells. Compound 8e was the most potent hybrid in reducing ROS and 15-HETE levels showing IC₅₀ values of 1.02 μM (11-fold more potent than that of celecoxib, IC₅₀ = 11.75 μM) and 0.17 μM (about 43 times more potent than celecoxib, IC₅₀ = 7.46 μM), respectively. Hybrid 8h exhibited an outstanding TNF-α inhibition with IC₅₀ value of 0.40 μM which was about 25 times more potent than that of celecoxib and diclofenac (IC₅₀ = 10.69 and 10.27 μM, respectively). Docking study of the synthesized hybrids into the active sites of COX-2 and 15-LOX enzymes ensures their favored binding affinity. To our knowledge, herein we reported the first 1,2,4-triazine-quinoline hybrids as dual COX/15-LOX inhibitors.

Multivalent butyrylcholinesterase inhibitor discovered by exploiting dynamic combinatorial chemistry

In this study, we report the generation of a polymer-based dynamic combinatorial library (DCL) incorporating exchangeable side chains using acylhydrazone formation reaction. In combination with tetrameric butyrylcholinesterase (BChE), the most potent binding side chain was identified, and the information obtained was further used for the synthesis of a multivalent BChE inhibitor. In the in vitro biological evaluation, this multivalent inhibitor exhibited not only better inhibitory effect than the commercial reference but also high selectivity on BChE over acetylcholinesterase (AChE).

Chemical Profile and Antioxidant Activity of Zinnia elegans Jacq. Fractions

Zinnia elegans (syn. Zinnia violacea) is a common ornamental plant of the Asteraceae family, widely cultivated for the impressive range of flower colors and persistent bloom. Given its uncomplicated cultivation and high adaptability to harsh landscape conditions, we investigated the potential use of Z. elegans as a source of valuable secondary metabolites. Preliminary classification of compounds found in a methanolic extract obtained from inflorescences of Z. elegans cv. Caroussel was accomplished using HR LC-MS techniques. The extract was then subjected to solid-phase extraction and separation using Sephadex LH-20 column chromatography, which resulted in several fractions further investigated for their antioxidant properties through lipoxygenase inhibition and metal chelating activity assays. Moreover, following additional purification procedures, structures of some active ingredients were established by NMR spectroscopy. The investigated fractions contained polyphenolic compounds such as chlorogenic acids and apigenin, kaempferol, and quercetin glycosides. Antioxidant assays showed that certain fractions exhibit moderate 15-LOX inhibition (Fr 2, IC50 = 18.98 μg/mL) and metal chelation (e.g., Fr 1-2, EC50 = 0.714-1.037 mg/mL) activities as compared to positive controls (20.25 μg/mL for kaempferol and 0.068 mg/mL for EDTA, respectively). For Fr 2, the 15-LOX inhibition activity seems to be related to the abundance of kaempferol glycosides. The NMR analyses revealed the presence of a kaempferol 3-O-glycoside, and a guanidine alkaloid previously not described in this species.

Replacement of an Indole Scaffold Targeting Human 15-Lipoxygenase-1 Using Combinatorial Chemistry

Human 15-lipoxygenase-1 (15-LOX-1) belongs to the class of lipoxygenases, which catalyze oxygenation of polyunsaturated fatty acids, such as arachidonic and linoleic acid. Recent studies have shown that 15-LOX-1 plays an important role in physiological processes linked to several diseases such as airway inflammation disease, coronary artery disease, and several types of cancer such as rectal, colon, breast and prostate cancer. In this study, we aimed to extend the structural diversity of 15-LOX-1 inhibitors, starting from the recently identified indolyl core. In order to find new scaffolds, we employed a combinatorial approach using various aromatic aldehydes and an aliphatic hydrazide tail. This scaffold-hopping study resulted in the identification of the 3-pyridylring as a suitable replacement of the indolyl core with an inhibitory activity in the micromolar range (IC 50=16±6 μm) and a rapid and efficient structure-activity relationship investigation.